When Walter Brun became a manufacturer, he presented a unique prototype at Le Mans. 

 

At the beginning of the 1990s, after a period of success and great victories with Porsche, driver and team manager Walter Brun was faced with a dilemma. He had two options: either resign himself to giving up motor sport because private teams were no longer welcome, or become a manufacturer of his own cars. The Swiss entrepreneur Walter Brun, determined to succeed, initiated the construction of the C91-Judd. A car conceived in response to a personal desire at a time when factory-backed racing was the dominant force. The Ascott Collection is pleased to present this rare Brun C91, which recently demonstrated its racing capabilities in Group C by Peter Auto.

 

1991, a pivotal year for Group C

The year 1991 marked a period of change in the world of endurance racing, with the programmed disappearance of Group C cars - still tolerated in 1991 - in favour of cars with 3.5 litre engines like those used in Formula 1. The new regulations ban turbocharged and rotary engines in favour of naturally aspirated engines with a maximum capacity of 3.5 litres. There is no limit to the number of cylinders. Chassis dimensions remain unchanged. However, the minimum weight has been significantly reduced from 900 kg to 750 kg. Carbon fibre is used throughout...

With the wind of innovation blowing, the Brun C91-Judd was unveiled at the 1991 Le Mans 24 Hours: Walter Brun came to reveal his prototype on the legendary circuit. On the Friday of the big week at Le Mans, he presented his creation in person... which, on the Wednesday, celebrated the racing debut of Porsche 962C n°17 (chassis #177), the very last of its kind to be assembled in Weissach. An ambassador for the Porsche brand and its loyal representative in the 1980s, Brun turned his back on the German company to embark on an adventure with his own car.

Walter Brun didn't have much of a choice. Porsche was interested in its own F1 project and didn't want to develop a 3.5 litre engine for customer competition. The 962Cs received a weight penalty in 1991 and were no longer competitive. He had extensively modified 962 chassis - even selling them to private teams - and was well aware of the car's limitations. The target weight of 750kg was impossible to achieve from a 962... So the Swiss built his own prototype. It was a stroke of luck for him to become an endurance constructor. He had just finished three unsuccessful seasons in F1 (at the end of 1990) and therefore had all the right contacts to find an engine adapted to the new FIA regulations.

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The Brun C91-Judd was developed by Walter Brun at Brun Technics, the engineering office he set up in Basingstoke in 1989 to support his involvement in Formula 1. In 1989, he set himself the ambitious goal of entering both F1 and endurance racing. By 1991, he was aiming to create a single-seater and a prototype (the C91) with a 12-cylinder 70° V engine called Neotech. With 48 valves, 640 bhp and 12,400 rpm, the engine was intended to serve as the common element between the two, but in the end it was never installed in either the F1 car or the prototype. Nevertheless, tests conducted in 1990 with a Porsche 962C yielded promising results. Unfortunately, no funding was forthcoming. For a period, Seat was approached with a view to participating in the project, but this was unsuccessful.

Despite the setback concerning the engine, the work carried out by Brun Technics seemed to be progressing well. By December 1990, 75% of the work had already been completed, according to the main person concerned. Wind tunnel tests with a 1/3 scale car were conducted at the MIRA Technology Park to validate the design.

The team of Steve Ridgers, John Iley and Hayden Burvill, responsible for designing the C91, initially planned to make room for the 12-cylinder engine, which explains the special design, particularly with the integration of the rear suspension. The design was created with the intention of providing maximum rigidity and support for the renowned block. The C91-Judd boasted a high cockpit, long rear and imposing spoiler similar to that of the Jaguar XJR-14, making it a modern, slender car. The project kept a small team busy and became Walter Brun's sole focus when Formula 1 was discontinued at the end of 1990.

The Judd V8 engine, derived from the one seen in F1 in the Leyton House CG901 and used by Walter Brun in F1, has now been installed. However, the possibility remains open to future customers of installing another block. For example, the team has positioned the water radiator at the front, freeing up space for cooling the oil radiators on the sides. The decision to house a Porsche turbo engine at the rear, with the intercoolers on the side, was made for technical reasons, with the aim of accommodating American customers who might wish to make this choice. The gearbox was developed by Brun, with Hewland supplying the internal parts. Advanced Composites is responsible for building the carbon fibre shell, while Comtec is responsible for the bodywork. Yokohama is responsible for the tyres, the manufacturer already being Walter Brun's endurance partner. BBS wheels, Brembo brakes and Bilstein shock absorbers are used. In short, only top suppliers are used. Assembly takes place in Stans, the capital of the Swiss canton of Nidwalden and Walter Brun's place of residence.

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In pursuit of factories

Walter Brun's ambition with his C91-Judd project is simple. He knows that he can't compete with the top teams straight away, and that it's impossible to compete with the official factories. Instead, as Peter Sauber did with Mercedes, Walter Brun wants to be noticed by a manufacturer and become its support team.

The Nürburgring race commenced with a challenging start for the C91-Judd team. Oscar Larrauri and Gregor Foitek were responsible for the car's qualifying performance, achieving a time of 1'29''872, which placed them 16th out of 21 competitors. Despite this, the team was confident that with further adjustments, the car would be ready for the race. Given the competitive nature of the event, this was not unexpected. Technical issues prevented the team from taking the start of the race. The real competition debut came in France, at Magny-Cours. The C91-Judd qualified 8th with a time of 1'27''722, just 1.5 seconds behind the Mercedes C291 of Michael Schumacher. Oscar Larrauri completed just four laps of the race before the oil from the C91-Judd spilled onto the track, resulting in his retirement. The rounds at Mexico City and Autopolis (Japan) ended in race retirements. In Mexico City, the starter failed during a pit stop, resulting in the driver retiring after 31 laps. In terms of pure performance, the C91-Judd set times comparable to some Porsche 962Cs and the Mazda 767B.

In Japan, the car qualified in 1:32.985, just 1.1 seconds behind the Mercedes C291 of JL Schlesser and J. Mass and 2.5 seconds behind that of M. Schumacher and K. Wendlinger, who went on to win the event. While the performance was there, the reliability was not yet at the required standard.

Transporting the cars to Mexico and then to Japan proved to be an expensive undertaking. Walter Brun undertook this challenge because he believed in his project and gave himself every chance of success. This inaugural season, which was too short, has enabled him to develop the car, which has improved in terms of performance. However, reliability is still a long way off. Walter Brun was confident about the future, but unfortunately everything came to an abrupt halt. Repsol, the team's main sponsor, withdrew. The C91-Judd was unable to be developed and remained in the garage. This marked the end of his brief career.

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The car was kept for 25 years by its previous owner and subsequently restored by its current owner

Walter Brun built just one example of the Brun C91, which therefore bears the chassis number C91-001. The Brun C91-001 was acquired directly from Walter Brun in March 1994 by its previous owner. It has been maintained and kept in remarkable condition, participating only in runs at Sebring and Daytona between 1998 and 2001.

In 2021, the Brun C91 was imported by its new owner from the west coast of the United States to England, where it was entrusted to Scott Sport for a complete restoration. After several months' work, the Brun C91 returned to the track at Spa Classic 2023. The car was fine-tuned by Alex Müller. The Brun C91 was then entered in the Dix Mille Tours du Castellet, where Alex Müller outperformed the competition to win both Group C races, clocking an exceptional time of 1' 47.70". This unique Brun C91 is now available for sale. This is a unique opportunity to own a superb car developed for the 1991 Sportscar World Championship, the championship that saw the racing of genuine Formula 1 bodyshells and the appearance of the dual rear wing, so characteristic of the cars from this period that has become mythical for endurance fans.